Intersex

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Introduction

  • Developmental abnormalities resulting in discordance between genetic, gonadal or phenotypic sex.
  • Includes true hermaphrodites, pseudohermaphrodites and other forms of sex reversal.


Hermaphroditism

  • Individual possessing gonads of both sexes.
  • Rare

Aetiology

  • Failure of embryological differentiation of gonads during foetal life leads to the presence of both ovarian and testicular tissue (ovotestis or one of each type).

Consequence

  • The tract is predominantly female, although there is often an enlarged clitoris and reduced vulval lips.
  • Usually XX with H-Y antigen (protein normally coded for by Y chromosome).


Pseudohermaphroditism

  • Gonads are of one sex and the ducts and external genitalia are modified towards, or are of, the opposite sex.
    • Male pseudohermaphrodite: Testis-like gonads and predominantly female genitalia.
      • Commonly found amongst pigs (and goats).
      • Affected animals behave like males and may mount.
      • There is a sub-anal genital opening with a prominent clitoris.
      • Testes may be in a scrotal structure or intra abdominal.
      • Poorly developed uterine horns which may contain mucus-like secretion.
    • Female pseudohermaphrodite: Ovary-like gonads and male-like genitalia,rare.


Aetiology

  • Genetic
    • In goats the characteristic is linked to a gene for polledness (dominant).
    • Chromosomal studies in pigs, goats and dogs (Cocker Spaniels) have shown that most pseudohermaphrodites are basically genetic female (XX sex reversal) despite the testis-like nature of their gonads.
  • XY gonadal dysgenesis (testicular feminisation syndrome)
    • Recognised in cattle and horses
    • Individuals are male pseudohermaphrodites with elevated testosterone levels.